The discussion below is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.
An aspect of the present invention relates to a wind turbine comprising a bearing seal, in particular to wind turbines with a direct drive generator, e.g. direct drive wind turbines of 1 MW or more. In wind turbines comprising a direct drive generator, the rotor is directly driven by the rotor. The main bearing is located between the housing ring and the rotor and is designed to absorb the gravitational and aerodynamic loads on the rotor. Particularly in direct drive systems without transmissions, diameters are large and circumferential speeds are high. The service life of the main bearing determines to a large extent the service life of the wind turbine as replacing the main bearing leads to high costs. In circumstances whereby the wind turbine is placed in difficult accessible locations, for instance at sea, replacing the main bearing during service life must be avoided. The service life of the main bearing depends to a large extent on the service life of the oil seals between the rotating parts and the stationary parts of the main bearing. These oil seals are required to ensure that sufficient lubrication means such as oil remains in the main bearing. The assembly and disassembly of oil seals requires dismantling of the equipment.
A wind turbine with a bearing seal is for example disclosed in WO 2004/015288. This bearing seal comprises a single two-piece seal at either side of the gap between the inner and outer bearing races. The complex labyrinth structure of the seal parts may considerably reduce the life time of the seals.